President Trump made one of his characteristically hysterical accusations over the weekend, tweeting that he "just learned" that former President Barack Obama had personally ordered his phones at Trump Tower to be tapped just before the election. This is, so far as can be discerned, 100 percent nonsense. Stephen F. Hayes at the conservative Weekly Standard spent some time trying to report the claims out, and concluded in part that "White House sources acknowledge that Trump had no idea whether the claims he was making were true when he made them."

And yet, Trump's claim was given a plausibility boost by the fact that the Obama administration really did build and operate a dragnet surveillance program. It's a real shame liberals didn't end it when they had the chance.

So what was Trump talking about? As Julian Sanchez writes, it appears that he was basing his claim on a garbled reading of several news articles discussing a possible FBI investigation of Trump-Russia connections, probably by way of a summary article published in Breitbart. (As a new MIT/Harvard study concludes, this sort of Breitbart funnel is now a major feature of right-wing media which constructs "true or partly true bits of information into a message that is, at its core, misleading.")

As liberals quickly pointed out, such an investigation is a very different thing from the president personally ordering a wiretap. Federal law enforcement is supposed to be semi-independent from the White House. It would both be wildly inappropriate for a president to decide which political opponents should be investigated and also totally within the FBI's purview to investigate candidates suspected of breaking the law.

But I'd bet my bottom dollar that Trump is just talking out of his hat. He is not legally astute and not a close reader. The whole episode smacks of a dim, angry partisan half-skimming an article and quickly jumping to a related but totally unsupportable conclusion.

Still, protests from various Obama administration officials about Trump's claim rang more than a little hollow. Here's Ben Rhodes, Obama's closest foreign policy adviser:

The Fourth Amendment is also supposed to protect Americans, by requiring government searches or seizures to be conducted under a warrant which describes "the place to be searched, and the persons or things to be seized." This amendment was systematically violated by the warrantless wiretapping program put in place by the George W. Bush administration.

But as we learned from the Snowden documents, not only did Obama not put government surveillance back on a constitutional footing, he in many ways expanded it. Obama kept Bush's NSA director and later promoted him. Under his administration the NSA ran a dragnet collection of all sorts of American communications, particularly internet and cell phone metadata, and traded data with ally nations to sidestep legal barriers on domestic surveillance. It worked to compromise commercial encryption. It developed a gigantic infrastructure to systematically record all phone conversations in entire nations, and tested it on the Bahamas and Afghanistan, and on and on.

Meanwhile, the whistleblower who revealed all this had to flee to Russia to avoid prosecution, and the journalist who revealed Bush's warrantless wiretapping scheme spent years being legally persecuted by the Obama Justice Department for not revealing his sources from another story. (There was eventually a surveillance reform law, but it was largely toothless.)

Again, Trump had no evidence for his claim, and it is most likely totally false. But if Team Obama had cleaned up the civil liberties disaster from the Bush administration properly, Trump would have a much harder time selling such nonsense.